Multiple closed nucleus breeding for swine production

ABSTRACT

The invention comprises use of first and second, and optionally additional further, genetically and information-linked swine nucleus breeding herds to transmit genetic improvement from the first herd to each of the other herds which can be closed to live animal introduction to provide benefits in addition to genetic improvement to both the first and second and any additional herds.

FIELD OF THE INVENTION

The invention relates to the production of swine and in particularaspects to methods and systems using two or more nucleus herds forbreeding and delivery of improved genetics with health to swineproducers. In one aspect, the invention relates to such methods andsystems in which two genetically linked nucleus herds are usedcooperatively to improve genetics in one or both herds. In otheraspects, the invention relates to such methods and systems comprisingmore than two nucleus herds.

BACKGROUND OF THE INVENTION

Animal breeding and production has changed significantly in recentdecades and ongoing concerns about animal health and transmissiblediseases will cause change to continue in the direction of increasingherd health. Further, as breeding has increasingly focused on polygenicand other low response traits, statistics and technology have come toplay an increasing role. One result of this trend has been thedevelopment and widespread use of the best linear unbiased prediction(BLUP) statistical model for predicting estimated breeding values (EBVs)for potential parents to be used in a breeding program. Such programsare well known and available to persons skilled in the art from a numberof sources and are capable of producing EBVs that to a considerableextent distinguish between genetic and environmental effects. BLUPprograms for use with swine are well known and available. One systemthat can provide advantageous results can be mentioned here, but otherprograms are available and the approach is well known to those skilledin the art of animal breeding. The MTDFREML (Multiple Trait DerivativeFree Restricted Maximum Likelihood) is a flexible set of programs,designed to be used with animal breeding data where an animal geneticeffect is used for each trait, that can be used to estimate variancecomponents using a derivative free restricted maximum likelihoodalgorithm. The programs are readily available. The program generatesBLUP solutions to the mixed model equations, contrasts of solutions,prediction error variances of solutions and contrasts, and calculatesexpected values of solutions. The programs are readily available fromDale Van Vleck at the University of Nebraska—Lincoln. As will befamiliar to those working in this area, some development of input andoutput routines may require development for particular applications, butthese are matters involving only the routine exercise of ordinary skill.

Since it is impractical to include all animals in the swine industry ina single breeding program because of costs and lack of control, geneticimprovement of swine breeding stock has tended to involve use ofrelatively few elite breeding units or genetic nucleus herds, forexample, at the top of pyramid structures to disseminate geneticimprovement to terminal swine produced for food. Open and closed nucleuspyramid breeding schemes are now extensively used to provide anadvantageous balance between rate of genetic improvement and rate ofinbreeding in producing breeding stock for terminal swine (non-breedingswine used for meat). The difference between open and closed nucleusherds is that in the closed system, the elite breeding herd is closed tothe importation of animals from other sources, whereas in open systemsthe elite breeding herd is open to such animals.

Genetic improvement is strongly dependent on abundant and goodmeasurement of phenotypic traits to be included or excluded for breedingand these measurements are a significant part of the cost and a majorcontributor to the accuracy of a breeding program. The phenotypicmeasurements can be turned into EBVs (Estimated Breeding Values), eitherdirectly or by including phenotypic data collected from animals acrossherds in different environments, so that genetic and environmentalinfluences on the data can be distinguished. If data are availablehaving good data structure (use of breeding animals across herds) andproper pedigree recording, BLUP can be advantageously used. Currently,systems for applying BLUP to molecular genetic markers as well as tophenotypic measurements are in preliminary use and under development andit is expected that these techniques will contribute to further improveswine breeding.

In addition to good measurements and good data structure, sophisticatedpyramid breeding systems require nucleus herds of sufficiently largesize to identify and track phenotypic and genetic markers of interestfor the desired genetic improvement. For traits having lowheritabilities or showing low levels of improvement per generation, evenlarger herds are needed to produce statistically meaningful results.These factors and others lead to the requirement of SGNs (swine geneticnucleus herds) of significant size to prevent inbreeding and be capableof reliable genetic improvement in respect of all of the traits ofcurrent interest. Since the cost of maintaining and improving large SGNshas been generally prohibitive for the producer of terminal swine, theSGNs have typically been maintained at facilities of commercial geneticssuppliers who then distribute animals and semen to producers for use inproducing dams and sires for breeding and cross-breeding and ultimatelyproducing terminal swine for the meat markets. As a result, however, theterminal swine producer has lost a measure of direct control over itsown breeding program and, as live animals are periodically introducedinto its herds, suffers the risk of pathogen importation as well.

As will be described below in more detail, the invention is directed tonew and improved methods and systems for breeding swine that makes iteconomically feasible for many producers that maintain terminal swine tohave an SGN at their own facilities under improved direct control by theproducers. In another aspect, the invention is directed to methods andsystems in which the producer's SGN is genetically linked to acommercial genetics supplier's SGN. In another aspect, the invention isdirected to the use of closed SGNs for these purposes therebyadditionally providing animal health benefits to the terminal swineproducers and ultimately to the meat consumer.

Such new and improved methods and systems for producing and deliveringgenetic improvement to swine producers consistent with maintaining ahigh degree of isolation among herds for insuring good animal health aregreatly needed and are provided in accordance with the different aspectsand embodiments of the invention.

SUMMARY OF THE INVENTION

The invention comprises the use of two or more genetically linked SGNsfor producing and delivering genetic improvement to producers ofterminal swine for meat. The SGNs comprise at least a SGN1 (sometimesreferred to as SGN1 characterized by a rate of genetic improvement and arate of inbreeding where the number of animals is sufficient forachieving and maintaining over multiple generations a desired balancebetween the rate of genetic improvement and the rate of inbreeding andat least one SGN2 (sometimes referred to as SGN2) characterized by asmaller number of animals insufficient to maintain that balance in theabsence of periodic introduction of germplasm. Except for animals fromthe SGN1 that are used to establish the SGN2, the SGN2 is closed tointroduction of live animals to greatly reduce or eliminate the risk ofhealth hazards due to introduction of live animals. The SGN is a closedSGN optionally with new germplasm introduced from time to time via semenor embryo transfer (ET) since periodically introducing new germplasminto the SGN1 herd may permit additional genetic improvement. Use ofpathogen-free semen for breeding is an advantageous way of introducingnew genetics into an SGN without opening the herd. After establishmentof the SGN2, germplasm and improved genetics introduction from SGN1 toSGN2 is limited to sperm or optionally embryos produced under conditionsinsuring freedom from diseases of concern. A key benefit or advantage ofclosing the SGN2 is to maintain the health of the producer's herds sinceby closing the herd to live animal introduction, the introduction ofunwanted pathogens can be reduced to a significant degree. Datacollected from both the SGN1 and the SGN2 are used periodically toprovide target measures of genetic improvement and to determineperformance measures for the SGN2. Using these methods and systems hasbeen found to enable rates of genetic improvement in the SGN2 to equalor exceed rates of genetic improvement in the SGN1.

According to the invention, the SGN1 and the SGN2 are genetically linkedto permit the use of statistical models such as BLUP that candistinguish genetic from environmental effects with phenotypic datacollected from both herds including, unless otherwise required by thecontext, molecular marker data derived from cellular samples from liveanimals. The genetic linkage is preferably provided by the use of semenfrom related or identical sires for breeding in both the SGN1 and theSGN2 herds and trait or data linkage is provided by collection and useof at least a core set of phenotypic data from the resulting offspringin both SGNs. Since the SGN2 can be significantly smaller than the SGN1due to the genetic linkage and trait data linkage, the invention makespossible establishment of an SGN at a swine producer's facility that isunder the producer's control to produce improvement in a desireddirection without the need for maintaining an SGN having the size andassociated costs of the SGN1. Thus, using an SGN2 with a SGN1 asdescribed herein, it is possible to accomplish the producer's goals ofsubstantially or completely eliminating live animal introductions foranimal health reasons, gaining control over genetic improvement, and atthe same time obtaining the benefits of genetic improvement via the SGN1that were previously only possible based on maintaining an independentSGN as known in the prior art.

In one embodiment the invention comprises method and system forproducing genetic improvement in swine in which a first swine geneticnucleus elite breeding herd or SGN1 is provided or made available at afirst site effectively isolated for purposes of preventing transmissionof selected pathogens to a second site at which is located a SGN2derived from the SGN1, the SGN1 having a rate of genetic improvement anda rate of inbreeding and a number of animals sufficient for achievingand maintaining over multiple generations a stable balance between therate of genetic improvement and the rate of inbreeding, the SGN2 havinga smaller number of animals than the SGN1, and the SGN1 and SGN2 furthergenetically linked by use of semen from the same or related sires inproducing offspring in both the SGN1 and the SGN2. Optionally, furthergenetic linkage can be provided by embryo transfer (ET). This embodimentfurther includes steps of using a core set of phenotypic data at leastsome of the traits of which are measured in both the SGN1 and the SGN2herds and generating a ranking of dams in the SGN2 for achieving atargeted measure of genetic improvement for a next succeeding generationin the SGN2 and using semen provided from sires in the SGN1 for use inbreeding dams in the SGN2 to achieve the targeted measure of geneticimprovement in the SGN2. According to a further aspect, the measure ofactual genetic improvement is also periodically determined and providedto the producer of the SGN2.

In another embodiment, the invention comprises method and system forproducing genetic improvement in swine comprising, relative to a firstswine genetic nucleus elite breeding herd or SGN located at a first siteeffectively isolated for purposes of preventing transmission of selectedpathogens, maintaining a second site at which is located a SGN2 derivedfrom the SGN1, the SGN1 having a rate of genetic improvement and a rateof inbreeding and a number of animals sufficient for achieving andmaintaining over multiple generations a stable balance between the rateof genetic improvement and the rate of inbreeding, the SGN2 having asmaller number of animals than the SGN1, and the SGN1 and SGN2 beingfurther genetically linked by use of semen from the same sires inproducing offspring in both the SGN1 and SGN2. This embodiment furtherincludes steps of selecting dams for breeding from a ranking of dams inthe SGN2 for achieving a targeted measure of genetic improvement for anext succeeding generation in the SGN2, and breeding the selected damsusing semen from sires in the SGN1 selected for use in breeding dams inthe SGN2 and periodically providing determined measures of actualgenetic improvement to the producer of the SGN2 to achieve the targetedmeasure of genetic improvement in the SGN2.

According to another aspect, the invention comprises method and systemfor determining measures useful in breeding swine comprising accessingat least a core set of phenotypic data obtained from each of a firstswine genetic nucleus breeding herd SGN1 and a second swine geneticnucleus herd SGN2, the SGN1 and the SGN2 being genetically linked; andproducing measures for at least one of the SGN1 and the SGN2 herdsselected from the group consisting of measures of estimated breedingvalues for selected traits and measures of rate of genetic improvementand combinations thereof.

In accordance with other aspects of the invention, the inventioncomprises methods and means for assisting the terminal swine producer inmanaging the breeding and cross-breeding of animals derived from an SGN1herd to improve genetic potential in an entire swine production systeminvolving multiple generations derived from the producer's own SGN2herd, for example, GGP (great grandparent), GP (grandparent), PS (parentswine) and multiple line crosses for producing MS (market swine orterminal swine “TS”) used only for meat and by-products. In otheraspects, the systems and methods in accordance with the invention can bemore cost effective and profitable for the swine producer than prior artsystems even without placing a value on health benefits.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates schematically swine production systems in accordancewith the prior art and a swine production system in accordance with theinvention comprising use of genetically linked SGN1 and SGN2 andoptionally other SGN herds.

FIG. 2 illustrates schematically establishment and maintenance of SGN2maternal line herd that corresponds to and is genetically linked to aSGN1 maternal line herd.

FIG. 3 illustrates schematically an embodiment of information flows usedin accordance with an aspect of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention is directed to improvements in the breeding and productionof animals to produce market swine. The swine lines to be bred can beselected from any breed of swine. Breeds or lines of swine, as thoseterms are generally used today, are animals having a common origin andsimilar identifying characteristics. Lines of swine are groups ofrelated animals produced, for example, but not exclusively, by linebreeding, the mating of animals within a particular line according to amating system designed to maintain a substantial degree of relationshipto a highly regarded ancestor or group of ancestors without causingunacceptably high levels of inbreeding. In particular aspects, theinvention relates to improvements in the breeding of maternal lines forthe production of market pigs, though the invention can be used withpaternal lines and other lines as well. A maternal line, as is wellknown, is a line that excels in the maternal traits of fertility,freedom from dystocia, milk production, maintenance efficiency, andmothering ability; while paternal lines are strong in paternal traitssuch as rate and efficiency of gain, meat quality, and carcass yield.

The invention comprises methods and systems for producing geneticimprovement in swine in which a SGN1 (first SGN—“swine genetic nucleuselite breeding herd”) at a first site and a second SGN (“SGN2”) at asecond site closed to live animal and associated pathogen introductionsare used cooperatively to effect genetic improvement in SGN2. Accordingto an aspect of the invention, a measure of genetic improvement isselected and a target measure of genetic improvement is set for SGN2 ina future period and a measure of achievement of genetic improvement(“performance measure”) is determined for SGN2 at intervals during andfollowing the period and is provided to the SGN2 producer. Asillustrated, the preferred measure of genetic improvement is the ratioi/t usually referred to by geneticists as the rate of geneticimprovement. The term i is described in more detail below, but may bereferred to as the selection intensity for a selected criterionexpressed in standard deviations. For swine, the generation interval tis usually defined as the average age of the parents at the time offarrowing of offspring for the next generation. The target measure andthe performance measure can be periodically provided directly to theSGN2 producer or can be compared to the target measure or to performancemeasures of other SGN herds to evaluate successful implementation ofgenetic improvement or to determine the existence of and be used inassessing correction of problems in SGN2 or to establish the targetmeasure for a succeeding interval.

The ratio i/t for swine can vary over positive and negative numbersaround zero up to an upper value that may approach a biological limitfor a given population. For dams, a reasonable upper value is about 1.50(assuming use of gilts for breeding to minimize generation interval t)while for sires a reasonable upper value is about 2.0 although in bothdams and sires somewhat higher values can also be observed with theimplementation of improved reproduction technologies. Sire upper limitstend higher than dam upper limits since intensity i for sires can behigher than for dams, which require a higher number of replacements, andtherefore cannot as a practical matter be subjected to the sameselection intensity as the sires. Use of embryo transfer (ET) canfurther increase the i/t ratio for dams in the direction of thatattainable for sires. Since it has surprisingly been found that in theabsence of target and performance measures, notwithstanding all of theother components of the described breeding systems, the performance ofthe SGN2 herd typically is on the order of about 0.3 or even less toless than about 0.5, a useful practical measure of achievement in SGN2is greater than about 0.5, more preferably greater than about 0.7 or0.9. Most preferably rates of improvement of 1.1, 1.3 or even 1.5 can beachieved.

As indicated, the preferred measure of genetic improvement is the rateof genetic improvement or i/t where i is selection intensity expressedas the difference between the mean selection criterion of thoseindividuals selected to be parents and the average selection criterionof all potential parents expressed in standard deviation units and t isthe generation interval measured in years. In this instance, the targetmeasure will be the predicted annual rate of genetic improvement of SGN2in standard deviation units and the performance measure will be theactual rate of improvement of SGN2 again in standard deviation units. Asis known, determination of i/t for SGN2 requires knowledge of i for bothdams and sires and therefore requires a collection and an exchange ofrelevant information (e.g., i/t for sires for SGN1 and i/t for dams forSGN2) to permit determination. Accordingly, a further aspect of theinvention comprises methods and systems to provide the relevantinformation to enable determination of i/t for SGN2 to and forgenerating the target measure and determining the performance measureand for generating further target measures.

Both target and performance measures are highly desirable andadvantageous for achieving the desired results of systems where SGN1 andSGN2 are used to produce genetic improvement in SGN2. In fact, in theabsence of such measures the rate of genetic improvements in herds hasbeen found to be on the order of 0.3 to less than about 0.5 althoughtheoretical rates of improvement were much higher. It appears thatperiodically providing the performance measures insures conducting theother operations to achieve the targeted results, as well as, moreconcretely, leading to rapid identification and correction of operatingproblems.

According to various embodiments, the invention comprises methods andsystems for producing genetic improvement in swine in which an SGN1 herdis provided or made available at a first site effectively isolated forpurposes of preventing transmission of selected pathogens to a secondsite at which is located an SGN2 herd. As used herein, a first site willbe effectively isolated from the second site if the SGN2 is totallyisolated from other swine, for example, not within a radius of a minimumof about 3, to about 5 miles or even more (10 miles or more) fromanother herd, and if there are strict biosecurity procedures followed atthe SGN2 site controlling human, animal and vehicular traffic, and if(preferably) the initial stocking of SGN2 from SGN1 occurs all at onetime. If additional stocking after initial stocking is to be used, thesubsequent stocking must flow through a quarantine facility to properlyscreen for pathogens.

According to various embodiments, the SGN1 herd has a rate of geneticimprovement and a rate of inbreeding and a number of animals sufficientfor achieving and maintaining over multiple generations a stable balancebetween the rate of genetic improvement and the rate of inbreeding inthe SGN1 herd.

To illustrate these aspects for SGN1, it is useful to look at the keyequation for genetic change in a herd. The key equation states that therate of genetic change in a selection criterion for any given trait (forexample, estimated breeding values—“EBV”, or other phenotypicinformation used as a basis for selection for that trait) is directlyproportional to three factors: accuracy of selection, selectionintensity, and genetic variation; and inversely proportional to a fourthfactor: generation interval. Mathematically, for any given trait, thekey equation can be writtenΔ_(BV) /τ=r _(BV,B{circumflex over ( )}V)σ_(BV) i/t,  (1)where Δ_(BV)/τ is the rate of genetic change per unit of time τ,r_(BV,B{circumflex over ( )}V) is the accuracy of selection (correlationbetween estimated breeding values and true breeding values for a traitunder selection), σ_(BV) is the genetic variation for the trait ofinterest, i is selection intensity expressed as the difference betweenthe mean selection criterion of those individuals selected to be parentsand the average selection criterion of all potential parents expressedin standard deviation units, and t is the generation interval (averageof parents' ages at the time of farrowing). (It is noted in passing thatthis equation also provides guidance for determining i/t since the rateof genetic improvement of any given trait (i/t) can be isolated from theequation.) This equation is well known and capable of readily being usedby those skilled in the art. From the equation, it will be clear thatthe producer's impact on the rate of genetic change will be primarilycontrolled by increasing selection intensity and by decreasinggeneration interval t to the extent practical.

In commercial breeding operations, a goal is to achieve an advantageousrate of genetic improvement, avoid disadvantageous levels of inbreeding,and maintain herd costs at an economically advantageous level. Thiscreates a tension between having a few highly elite animals for breedingto increase selection intensity and reduce breeding costs and having alarge number of breeding animals to prevent inbreeding depression.Consequently, it is advantageous to design breeding programs so as tobalance the Rate of Response and the Rate of Inbreeding and if possiblefind an advantageous balance between the two consistent with economy ofoperation. This process in general terms is well known in the art andneed not be further explained here, except for convenience to note thatthe rate of response per generation is illustrated above by equation (1)and that the rate of inbreeding and its relationship to breeding herdsize can be illustrated by equations (2) and (3) below:ΔF=½N _(e)  (2)where ΔF is the rate of inbreeding per generation and N_(e) is theeffective population size of the breeding population:N _(e)=4N _(m) N _(f)/(N _(m) +N _(f))  (3)where N_(m) and N_(f) are the number of males and the number of femalesused as parents for each generation. By iterative use of these formulasor computer modeling of these formulas for desired traits and rates ofresponse and availability of facilities for stocking and breeding,persons skilled in the art readily determine advantageous herd sizes foreach specific situation encountered in breeding and can likewisedetermine appropriate herd sizes in accordance with the invention inlight of the disclosure herein.

According to embodiments of the invention, the methods and systemsaccording to the invention can be used for any nucleus herds used inbreeding. It has been found particularly advantageous to use theinvented methods and systems in connection with breeding and productionof maternal line parent dams for breeding by paternal line terminalsires for the production of terminal swine because of the significantlylarger number of dams otherwise required and the corresponding greaterbenefit to be obtained from the methods and systems disclosed herein. Asa result, a preferred embodiment described herein relates to breedingand production of maternal line parent dams, but the invention can bereadily applied by those skilled in the art to other nucleus breedingsystems and for other lines including paternal lines.

According to an aspect of the invention, for example, referring tonucleus maternal line herds, both the genetics supplier's maternal lineSGN herd (sometimes referred to as SGN1) and the producer's maternalline SGN herd (sometimes referred to as SGN2) can be smaller thanotherwise would be necessary to achieve advantageous results. The twoherds (SGN1 and SGN2) must be genetically linked as discussed in moredetail below. The extent to which the genetics supplier's herd can bereduced in size depends in part upon whether the phenotypic datacollected by the producer is sufficiently accurate and reliable to meetthe supplier's requirements for data to be used in determining EBVs forthe genetics supplier's herds. In any event, it will be immediatelyclear to the skilled person that the SGN2 herd can be much smaller whenit is genetically linked to and supported by accurate information fromthe SGN1 herd than would otherwise be possible.

Referring in more detail to an exemplified nucleus maternal line herd,as a practical matter, it will usually be desirable to have no fewerthan about 50 dams in the SGN2 herd to provide at least about 3 damscoming into heat on a weekly basis to provide an advantageous rate ofbreeding work for planning and staffing purposes. As described below, ina preferred embodiment, no sire or boar stud herd is maintained for thesecond nucleus herd because semen from the SGN1 herd is obtained andused to provide genetic linkage between the herds. The upper boundary ofherd size for the producer's SGN2 herd will be determined by thebreeding program and number of parent sows required for producing thedesired number of terminal swine on a regular basis as well as producingreplacement swine. Thus the breeding SGN2 herd can range from about 50,which can support up to about 50,000 parent dams per year, to about 100,which can support about 100,000 parent dams per year, or to about 1000,which can support up to about 1,000,000 parent dams per year, or cantake other values depending on the number of parent dams to be producedeach year.

Referring now to the first nucleus maternal line herd SGN1 to illustratethe effects of aspects of the invention on herd size in the geneticssupplier's maternal line herd, consider, for example, that a minimumsize to prevent unacceptable inbreeding in the SGN1 herd has been foundto be about 450 sows. Additionally, of course, it is necessary toincrease the dam herd by a number sufficient to provide replacement damsfor the dam herd and boars for the stud herd. Further increases in sizewill be necessary if culls (animals excluded from selection forbreeding) constitute a significant portion of the offspring or for otherreasons such as health or to provide a sufficient population for adesired weekly breeding schedule or the like. As a result of using theinvention, and even without use of the external herd SGN2 data forcalculating EBVs for internal (to the genetics supplier) SGN1 breedingpurposes, it will be possible to reduce the size of the SGN1 herd towardthe minimum size needed to balance rate of response and rate ofinbreeding by significantly reducing the number of animals maintainedfor replacement breeding due to that portion of the herd necessary forproduction of those dams having been in effect transferred to the SGN2herd.

Further advantage can be obtained if the producer's collected phenotypedata can be used in determining EBVs for the genetics suppliers SGN1herd. For example, when a producer initiates an external genetic nuclearherd system as described herein, there may be a delay between when theproducer's data collection practices are sufficient to result inreliable improvement in SGN1′ herd and the time when the data accuracymeets the genetics supplier's standards. However, as soon as the datacan be reliably used for determining EBVs for the genetics supplier'sSGN1 herd, it is apparent that the genetic supplier will be able toincrease accuracy of prediction for selected traits. Likewise, referringagain to FIG. 1, as additional external closed SGN herds (SGN3, SGN4,etc.) come into use that are also genetically linked and data linked toSGN1, further improvements in accuracy can be achieved, provided that asufficient size herd to prevent unacceptable inbreeding is maintained.

According to various embodiments, as can be seen from the abovediscussion, the SGN2 can have a significantly smaller number of animalsthan the SGN1. The size for the SGN2 herd is targeted at a minimum of 50sows or the appropriate number of female animals to provide breedingdams for cross-breeding as practiced for producing parent dams used forproducing terminal swine, and additionally replacement dams for the SGN2herd itself. Another consideration influencing SGN2 size includesproviding enough dams to provide a steady average supply of replacementfemales on a regular (e.g., weekly) basis to permit the effective use offacilities, labor and supplies.

According to the invention, the SGN1 and SGN2 are genetically linked byuse of semen from the same or related sires from SGN1 or by use ofembryo transfer or other advanced reproduction techniques to produceoffspring in both the SGN1 and the SGN2 herds that to some known degreeshare a specifiable pedigree. According to a preferred aspect of theinvention, the desired genetic linkage is provided by using sires fromthe SGN1 to provide semen for breeding both of the SGN1 and SGN2 herds.The result is that, all of the offspring of the prescribed matings inboth herds are half-sibs at least in respect of certain animals in eachherd, i.e., there are groups of half-sibs sharing a common pedigree, andphenotypic data collected from both herds are capable of being jointlyprocessed using conventional and available BLUP computer programs. Othermeans of providing genetic linkage can also be utilized, including butnot limited to use of semen from related sires and other techniquesuseful for causing offspring to share a pedigree as herein defined.

According to further aspects of some embodiments of the invention, theinvention includes steps of generating a ranking of dams in the SGN2 forachieving a targeted measure of genetic improvement for a nextsucceeding generation in the SGN2 and using semen provided from sires inthe SGN1 for use in breeding selected dams in the SGN2 to achieve thetargeted measure of genetic improvement in the SGN2. Likewise, accordingto some aspects of the invention, performance measures are likewisedetermined using information from both SGN1 and SGN2 and periodicallyprovided to the SGN2 producer.

A key priority in producing reliable phenotypic data is the clearidentification of the measurements (“tests”) to which the swine will besubjected and the conditions under which the swine will be maintainedduring the test period. For maternal line swine, the test periodtypically begins upon farrowing and ends upon the making of a decisionfor which testing was prerequisite, such as return of offspring to theparent herd as a replacement animal, shipment to market, and the like,after which the offspring may be said to be “off-test”. As discussedbelow in more detail, a minimum set of data comprises reproduction data,a more extensive set of data comprises reproduction data and growth ratedata (e.g., weight at off-test and the like), and a very advantageousset of data comprises reproduction data, growth rate data and predictedcarcass data. Many measures of those traits and techniques for makingmeasurements of those traits are known to those skilled in the art, andwhile a few of these are specifically described herein, the invention isnot limited to those mentioned but extends to all phenotypes and testsuseful for breeding purposes in accordance with the different aspects ofthe invention.

To illustrate the generation of ranking of dams in the SGN2, considerfirst that the phenotypic measurements required will depend on thetraits being enhanced. For maternal lines, desirable traits and datainclude for purposes of illustration at least reproduction traits anddata such as litter size, underline, and the like, growth traits anddata such as growth rate such as weight at off-test, and carcass traitsand data such as percent lean, back-fat and loin-eye area measurements.The SGN1 herd can be preferably evaluated for all of the traitsmentioned above and the SGN2 herd is preferably evaluated for at leastreproductive traits and more preferably for one or more of the growthtraits and carcass traits.

To increase the accuracy of EBV predictions it is of course highlydesirable that the measurements of both herds are made using the sametechniques and most preferably using personnel who have receivedsubstantially the same quality training in using those techniques.

According to aspects of the invention, the resulting phenotypic data canbe used to produce rankings, for example of dams in the SGN2 herd, fromwhich the most desirable animals for achieving the targeted improvementcan be bred with semen from SGN1. Preferably, the rankings are generatedusing BLUP computer programs to which data from both the SGN1 and theSGN2 herds can be input.

As indicated above, it may be desirable in some instances, but not inothers, to use data from the SGN2 herd for generating EBVs for the SGN1herd. Flexibility in this respect can be achieved by giving data fromeach animal indexes indicative of source and location and by makingmodifications either to the input routines or to the BLUP programsthemselves to access the appropriate data for the herd and traits whoseEBVs are being determined. Likewise, the outputs from BLUP programs, ifin the values of the traits measured, can be readily weighted usingeconomic information to maximize economic value for each assortment orconstellation of traits. Such input and output routines andmodifications are well known to those skilled in the art and can bereadily implemented if not already available in the BLUP programs beingused.

As previously discussed, the BLUP programs are well known and commonlyused in swine breeding and are readily available to those skilled in theart. An advantageous system for producing BLUP values is the MTDFREMLsystem available from Dale Van Vleck at the University ofNebraska—Lincoln. Other systems known and available to those skilled inthe art can also be used and adapted for use with data as describedherein by the routine exercise of programming skills.

In most SGNs, although it is possible to synchronize estrus by weaning,as a practical matter females are bred as they come into estrus duringthe course of the year. In contrast, elite sires or semen from elitesires may be available at most times unless the demand for semen isexcessive. Consequently, according to an aspect of the invention, it isuseful to generate the dam rankings on a periodic, preferably weekly,basis using currently available data so that as individual elite damscome into estrus they can be bred using semen from available eliteboars. Desirably, the herd size is managed so that on average a certainnumber, for example, 3 or more come into estrus each week, since apredictable rate of females in estrus permits determining the amount ofsemen or size of the boar stud herds that will be required as well asspreading personnel and facilities costs throughout fiscal periods.According to a preferred aspect of the invention, the dam rankings forthe SGN2 herd can be generated at any convenient period or interval,e.g., monthly or preferably weekly to provide very advantageous resultsin implementing a breeding program to improve herd genetics. Generally,most large producers practice weekly flow and weekly reports are mostadvantageous. Accurate information reporting from the producer herd siteto the genetics supplier site is required, reporting bred and farroweddams, so that the weekly dam rankings consists only of “open” dams, thatis, dams that are not bred and are available for breeding.

Since the dam rankings are provided to the SGN2 producer, that producerhas an increased measure of control of improvement in the SGN2 herdcompared to prior art use of only an SGN1 herd. For example, bymaintaining an SGN herd and increasing selection pressure, the SGN2 herdcan potentially achieve progress at a faster or slower rate in respectof selected characteristics relative to the SGN1 herd. A major factor inachieving desirable rates of genetic improvement as indicated by keyequation (1) above is provided by generation interval and to the extentthat the producer breeds lower parity females and highest rankedfemales, the producer further can further accelerate geneticimprovement. Also, since the data for the SGN2 herd can be collected bythe SGN producer, additional effort to achieve good data structure andaccuracy will also lead directly to improved genetics in the SGN2 herd.All of these advantages can be achieved in accordance with the inventionwhile maintaining the advantages of having SGN1 and SGN2 herds closedrelative to each other following the initial establishment of the SGN2herd.

According to an aspect, the invention includes a feature of using thesteps of generating a ranking of dams in SGN2 and using semen providedfrom sires in SGN1 for use in breeding dams in the SGN2 to achieving atargeted measure of genetic improvement for a next succeeding generationof SGN2. To illustrate this point, consider that the two herds SGN1 andSGN2 could be established and remain closed to each other after initialestablishment, thereby achieving the animal health benefits of thepresent invention, and semen from selected sires in the SGN1 herd couldbe used to transfer genetic improvement to SGN2. However, in the lightof the present invention, it can be seen that this system would not becapable of producing a targeted measure of improvement in the SGN2 herdbecause of the absence of dam selection in the SGN2 herd. In retrospectalso, it can be seen that in order to accomplish dam selection, it isnecessary to collect data representative of some of reproductive, growthand carcass traits and more importantly to use that data to generate theranking of dams. Even more important was the recognition that the use ofsemen from SGN1 to close SGN2 for health reasons also provided a geneticlinkage between the two herds that permitted determination of EBVs forSGN2 in addition to SGN1.

According to another embodiment of the invention, the inventioncomprises method and system for breeding swine comprising determiningmeasures for breeding swine. At least a core set of phenotypic dataobtained from each of a first swine genetic nucleus breeding herd SGN1and a second swine genetic nucleus herd SGN2, the SGN1 and the SGN2being genetically linked is accessed; and measures for at least one ofthe SGN1 and the SGN2 herds selected from the group consisting ofmeasures of estimated breeding values for selected traits and measuresof rate of genetic improvement and combinations thereof are produced. Ina further aspect, measures are produced for each of the SGN1 and SGN2herds. In yet further aspects, at least a core set of phenotypic datafrom each of an additional set of swine genetic nucleus breeding herdsis accessed, each SGN genetically linked with at least one other of aresulting total set of swine genetic nucleus breeding herds SGNs; andmeasures are further produced for at least one of the resulting totalset of SGNs.

According to preferred aspects of this embodiment of the invention, themeasures of estimated breeding values or of genetic improvement aredetermined using a best linear unbiased prediction (BLUP) statisticalmodel. For example, phenotypic data relevant to selected traits from atleast one of SGN1 and SGN2 can be provided by a data link to a databasethat is data linked to a data processor for producing the measures ofestimated breeding values, and then the data processor is used to accessthe database to produce the measures of estimated breeding values or ofrate of genetic improvement.

According to more preferred aspects of this embodiment of the invention,the measure is a measure of rate of genetic improvement for at least oneof SGN1 and SGN2 and the invention comprises producing a measure of rateof genetic improvement for at least one of SGN1 and SGN2; and themeasure of genetic improvement is provided by a data link to a siteassociated with the swine genetics breeding herd for which the measureis produced. At the site where the SGN is located, the measures are thenused, for example, for measuring compliance with a predeterminedbreeding plan for the SGN associated with that site or for improvingcompliance with the breeding plan upon occurrence of a provided rate ofgenetic improvement differing from a target rate of genetic improvementassociated with the breeding plan or for adjusting a target rate ofgenetic improvement associated with the breeding plan upon occurrence ofa provided rate of genetic improvement differing from the target rate.

According to another aspect of the invention, a ranking of dams in theSGN2 herd is periodically generated for achieving a targeted measure ofgenetic improvement for a next succeeding generation in the SGN2 herd;and the ranking is provided for use for selection of dams for breedingusing semen from SGN1 selected for use in breeding dams in the SGN2 toachieve the targeted measure of genetic improvement in the SGN. Forhighly advantageous results, this ranking of dams is generated andprovided weekly to the SGN2 producer.

Commercial breeders usually desire to take advantage of line or breedcomplementarity, an improvement in the overall performance of crossbredoffspring resulting from crossing lines or breeds of different butcomplementary biological types. In swine, line complementarity typicallycomes from crossing maternal lines (lines that excel in maternal traitssuch as fertility, litter size, mothering ability, and maintenanceefficiency) with paternal lines (lines that are strong in paternaltraits such as rate and efficiency of gain, meat quality and carcassyield) where the maternal and paternal lines are complementary to eachother. The ultimate in line complementarity is achieved in terminal-sirecrossbreeding systems in which maternal-line females are mated topaternal breed sires to produce progeny that are especially desirablefrom a market standpoint. Daughters of terminal sires are not kept asreplacements but are sold along with their male counterparts as marketanimals.

According to the invention, there are provided methods and systems forbreeding and producing terminal swine for meat. The invention isillustrated using a crossbreeding swine production system utilizing bothmaternal lines and paternal lines for ultimately producing animals formeat, and the closed external SGN herd described herein specificallyrelates to a closed external SGN herd for producing maternal line damsthat can be bred with paternal line terminal boars for producingterminal swine for meat production. However, the invention is notlimited to the particular embodiment described but can be extended toany system for genetic improvement of swine lines in which (1) a centralSGN herd and at least one external SGN herd (2) are bred using at leastone parent, usually the sire, of known genotype to provide geneticlinkage between offspring of the two herds sufficient for jointlyprocessing data from both herds using currently available best linearunbiased prediction (BLUP) programs, (3) relevant data for determinationof EBVs of potential parents in at least the external SGN herd arecollected from offspring of both herds; (4) EBVs are determined for atleast potential dams in the external SGN herd and (5) the external SGNherd is genetically improved by selection using the resulting EBVscalculated from both herds with imposition of target rate of geneticimprovement criteria such as i/t for the SGN2 herd.

Referring now to FIG. 1, FIG. 1 illustrates schematically swineproduction systems in accordance with the prior art at A, B, C and aswine production system in accordance with the invention at D comprisinguse of both a central nucleus breeding herd SGN1 and an external nucleusbreeding herd SGN2. In D, the maternal line stud and dam herds arepreferably isolated and all breeding is controlled in accordance with abreeding program determined as described herein. Thus, at A, there isillustrated the prior art use of a central SGN1 herd at 12 that is usedto provide genetically-improved maternal line boars (semen) or sows orboth to a multiplier facility 14 that in turn is used to provide damlines for producing terminal pigs for feeding, finishing and harvesting16. While system A illustrates all functions without segregation ofentity or space among the various functions, in practice the functionsare usually separated among entities or space or both as schematicallyillustrated at prior art systems B and C in which dashed lines 28 and 38indicate different entities or different locations or both, and in whichthe reference numerals of B and C (and D illustrating the inventiondiscussed below) correspond to those of A by their final digit.

Referring now to system D, D illustrates a system in accordance with theinvention in which a swine genetics provider 12 having a SGN1 herd, inaddition optionally to supplying swine genetics to traditionalfacilities B or C or both, also on a one-time or infrequent basisprovides stock to establish an external SGN maternal line dam herd (or aplurality of mate mal line dam herds) at a producer facility D. (Inaddition to the single external SGN herd shown at D, there may be one ormore other external SGN herds SGN_(1,2, . . . n) also established forother producers or facilities and these additional herds can benefitboth genetics supplier 12 and producer D as explained in more detailherein.

Referring now to FIG. 2 in detail, FIG. 2 illustrates D in FIG. 1 ingreater detail. Specifically, FIG. 2 illustrates that the SGN herds 12of the genetics supplier of FIG. 1 may comprise a plurality of pure linedam herds 12′ and pure line sire herds 12″ which can be used forproducing market swine (MS). As illustrated by line 110, at the time ofinitial establishment of the external SGN2 maternal pure-line herd 42,live female animals of SGN1 stock, optionally bred sows, may be providedafter thorough health screening on a one-time or at least non-routinebasis to the producer as shown by herd 112. At the time of establishingherd 112, maternal line semen from stud herd 102 can also be provided(illustrated by dashed line 106 from the genetics provider for initiallybreeding the SGN2 females by single sire matings resulting in offspring.Thereafter, the producer selects elite dams from the SGN2 offspring forbreeding with elite boars whose semen is provided by line 106 from thegenetics supplier. With good testing, selection and mating practices, itwill therefore be possible to impose selection intensity to improve theSGN2 herd in some instances at a more rapid rate than is necessarilyaccomplished in the SGN1 herd.

Those skilled in the art will appreciate that the result of using semenfrom the same sires for breeding SGN1 herd 103 and for breeding SGN2herd 112 is that the prescribed offspring from both herds will behalf-sibs, that is, there are groups of half-sibs in both herds, sharinga common pedigree and therefore that EBVs can be determined for bothSGN1 herd 103 and SGN2 herd 112 using conventionally available BLUPprograms. To illustrate, by using single-sire matings for all females,it will be known that the male selected for each female sired alloffspring from that female of SGN2 herd 112. Assuming for purposes ofillustration that the goal of breeding is to enhance production of largenumbers of dams with large litter sizes, good mothering ability, goodgrowth rate and good carcass characteristics, the offspring at birth canbe tagged with a unique animal identification. All females from littersin SGN2 showing specific abnormalities such as atresia ani, scrotalrapture, cryptorchidism or hermaphroditism are not eligible for the SGNbreeding pool and can be culled. The remaining females may be takenoff-test at the same time (about 165 days), weighed, and tested forbackfat and loineye area, and thereafter closely evaluated for physicalcharacteristics per selection guidelines until final selection for beingreturned to SGN2 herd 112 for breeding. The resulting collected data ofthe non-culled animals can then be processed by BLUP to provide EBVratings for each animal and the EBV ratings can be provided to theproducer for use in selecting females in herd 112 for breeding.

Concurrently, the sires of herd 102 can be culled, tested, and selectedin a similar way and EBVs determined for potential sires for the nextbreeding of females in herd 112.

According to aspects of the invention, the producer of herd 112 canestablish a targeted measure of genetic improvement or change. Ingeneral terms, about half of the improvement will derive from the siresselected for breeding from herd 102 and about half of the improvementwill derive from the dams selected for breeding from herd 112. As apractical matter, since a single boar can be used to breed a number ofsows, much of the selection pressure on herd 112 will derive fromscrupulously following selection guidelines within herd 112. The regularreporting of actual genetic improvement has proved to be instrumental inachieving results that theoretically could have been achieved withoutthe weekly reporting of actual improvement measures. The feedback loopcreated by providing the results actually obtained facilitates finetuning of the practices of herd 112 management and actually permits thetargeted measures of improvement to be achieved.

In this system, it will be seen and appreciated by persons skilled inthe art that by using semen from genetics provider 12 in external SGNherd 42, the resulting animals are preferably all half-sib animals ofcorresponding animals in the genetics provider's central SGN herd 12that may be produced using the same maternal line boars. Use of relatedrather than identical sires results in a lower, but still useful forBLUP, degree of genetic relationship. This use of common male geneticspermits phenotypic data collected from animals produced in external SGNherd 42 and phenotypic data collected from half-sib animals in theoriginating SGN herd 12 to be processed using BLUP to produce EBVswithout the necessity of maintaining the external SGN herd at a numberof animals which would by itself be sufficient to guarantee a sufficientlevel of heterozygosity and control of inbreeding in the external SGNherd. Simultaneously, it permits EBVs determined for the central SGNherd to have a greater accuracy level than would have been possible inthe absence of the external SGN herd. As more external SGN herds areestablished as illustrated by D′ in FIG. 1, further efficiencies can beachieved.

To illustrate, if additional external herds SGN3, SGN4, etc. are added,the resulting increased numbers of related animals permits more preciseestimation of EBVs for all of the herds whose data can be used.Moreover, comparison of target measures and performance measures ofgenetic improvement over a number of sites helps to identify facilitiesthat are failing for one reason or another to achieve the rates ofimprovement that they are capable of achieving and therefore provides ameasure of competitive efficiency for the operators of those facilities.

Referring again to FIG. 2 and in particular to the multiplier function44, during multiplier function 44, producer 40 can further breedselected maternal line females derived from the SGN2 herd in accordancewith the invention using semen or boars derived from genetics supplier12 as indicated by dashed line 126 to produce great-grandparent stock(GGP) as illustrated by 151. As, illustrated, the multiplier function 44can include steps cross breeding using a number of pure lines from thegenetics supplier herd GN2, GN3, and the like, for example, asillustrated by lines 121 and 131, consisting of sire herds 122 and 132and dam herds 123 and 133 respectively to produce GGP and GP(grandparent) dam herds 151 and 161 respectively. As illustrated,producer 40 can obtain semen for each of the intermediate breeding stepsfrom the genetics supplier via lines 121 and 131. The end result ofthese breeding steps is the production of a sufficient number of parentswine (PS) dams 171 for breeding with a external terminal boar lineillustrated by GN4 whose semen can be provided for example asillustrated by line 141 to produce market swine (MS).

According to a preferred embodiment of the invention, as illustrated inFIG. 2, the only introduction of live animals illustrated by solid line110 from the genetics supplier to the producer occurs on a one-timebasis at the time of establishing the external SGN2 herd. All othergenetics introduced into the producer's facilities is via semen asindicated by dashed lines 126, 136 and 146. In the instance of the SGN2herd 112 and optionally derived dam herds 151, 161, and 171 it can bedesirable for the producer to establish boar stud herds for use with theproducer's dam herds. By limiting live animal introductions in this way,the external SGN2 herd is a “closed” herd, that is, not open to furtherlive animal introductions, and as a result will advantageously isolatethe herd from negative health impacts that result from live animalintroductions.

Following establishment of the external SGN2 herd, genetics provider 10and producer 40 implement data collection and analysis suitable fordetermining EBVs of the external SGN2 herd using BLUP. While there aremany ways this can be accomplished, FIG. 3 illustrates the core of theprocess. Referring now to FIG. 3 in detail, FIG. 3 illustrates a systemfor providing, accessing and processing phenotypic data collected fromthe SGN1, SGN2, etc. herds as described herein and processing the datato provide EBV data and dam rankings to the producer 40 and measures oftarget and performance measures of genetic improvement as describedherein.

As illustrated in FIG. 3, animal identifier and phenotypic datacollected from each of SGN1, SGN2, and SGNn herds referenced by 301,302, and 303 are provided by data links 311, 312, 313 respectively to aplurality of databases 321, 322, 323, or optionally all databases can bepart of a single database as illustrated by reference numeral 325. Asused in this application, the term data link is used to refer to allinput, output, and transmission devices and methods that can be used toprovide data in electronic form from various sites to the data base andto return data to the appropriate sites. Thus, the term can includehand-helds, laptops, personal computers, scanners, and the like as inputdevices, electronic links both wired and wireless, via the internet orvia other data connections from input/output devices to the data baseand to the sites where information is used. Such matters are well knownin the art and those skilled in the art can develop many systems inaccordance with the teaching of the invention to accomplish the datatransfer, processing and use.

The animal and phenotypic data provided to the databases can be animalidentifier data, pedigree data, and phenotypic measurements for Traits1, 2, . . . , n as illustrated as well as other useful data identifiedfor particular applications as is known to those skilled in the breedingarts. Since, as illustrated in FIG. 2, semen for breeding SGN1, SGN2, .. . , SGNn comes from the SGN1 herd, it will be appreciated that sirephenotypic data for all the herds will be input from the SGN1 site inthe usual instance while the dam phenotypic data will be input from therespective herds containing the dams.

Periodically, a data processor 341 accesses selected data from database325 or its constituent data sets 321, 322, . . . , 323 and obtains therelevant phenotypic data representative of SGN1, SGN2, . . . , SGNnherds for determining EBVs and economically-weighted EBVs of the dams ofselected herds using BLUP and to provide a ranking of dams in each herdfor selecting dams for breeding. Likewise, the data processor accessesselected data from the database and selects sires most suitable forbreeding to achieve desired characteristics in the offspring. Theranking data is provided, for example, by data links 351, 352, . . . ,353 back to the respective herds where the data is needed forimplementing a breeding program, including selection of sires andranking of dams for semen provision and breeding respectively.

According to another aspect, the animal and phenotypic data for each SGNare used to generate measures of genetic improvement for each SGN and toprovide those measures back to at least the respective SGN. Asillustrated by the double-headed arrow 331, the measures of geneticimprovement can also be stored in the database 325. Preferably, both thedam rankings and the measures of genetic improvement are determined on aregular basis, for most advantageous results to accomplish a targetedmeasure of genetic improvement on a weekly basis, though other intervalscan also be useful.

While the invention has been illustrated in terms of various embodimentsembodying various aspects, the invention is not limited to theembodiments described herein in detail but by the claims appended heretointerpreted in accordance with applicable principles of law.

1. A method for producing genetic improvement in swine comprising: a.providing a first swine genetic nucleus elite breeding herd (hereinafterreferred to as an “SGN”) at a first site effectively isolated fromtransmission of selected pathogens from a second site at which islocated a SGN2 derived from the SGN1, the SGN1 having a rate of geneticimprovement and a rate of inbreeding and a number of animals sufficientfor achieving and maintaining over multiple generations a stable balancebetween the rate of genetic improvement and the rate of inbreeding, theSGN2 having a smaller number of animals than the SGN1, and the SGN1 andSGN2 being further genetically linked by use of semen from the samesires in producing offspring in both the SGN1 and SGN2; b. generating aranking of dams in the SGN2 for achieving a measure of geneticimprovement for a next succeeding generation in the SGN2, optionally atarget measure of improvement; c. providing semen from sires in the SGN1selected for use in breeding dams in the SGN2 to achieve the measure ofgenetic improvement in the SGN2; and d. wherein the actual measure ofgenetic improvement in the SGN2 is determined at intervals and used foreffecting genetic improvement in the SGN2.
 2. The Method of claim 1wherein the SGN1 and the SGN2 comprise SGNs for producing maternal lineparent dams enriched in maternal traits for producing terminal swine. 3.The Method of claim 1 wherein offspring from the SGN1 and the SGN2 areevaluated for at least a core set of phenotypic data and the core set isused for generating the ranking of dams in the SGN2.
 4. The Method ofclaim 1 wherein dams from the SGN2 are bred using semen from otherlines, optionally from sires maintained in a boar stud herd at thesecond site, for producing via one or more crossbreeding steps, parentdams for producing terminal swine.
 5. The Method of claim 1 wherein thecore set of phenotypic data comprises, for the SGN1 and SGN2,reproductive data, off-test weight, and carcass data.
 6. The Method ofclaim 1 wherein the core set of phenotypic data comprises, for the SGN2,reproductive data and off-test weight.
 7. The Method of claim 1 whereinthe core set of phenotypic data comprises, for the SGN2, onlyreproductive data.
 8. The Method of claim 1 wherein the step ofgenerating the ranking comprises use of a best linear unbiasedprediction (BLUP) algorithm.
 9. The Method of claim 1 wherein a dam herdfor the SGN1 comprises more than about 450 animals.
 10. The Method ofclaim 1 wherein a dam herd for the SGN2 comprises at least about 50animals.
 11. A method for producing genetic improvement in swinecomprising: a. maintaining, relative to a first swine genetic nucleuselite breeding herd (hereinafter referred to as an “SGN”) located at afirst site effectively isolated from transmission of selected pathogens,a second site at which is located a SGN2 derived from the SGN1, the SGN1having a rate of genetic improvement and a rate of inbreeding and anumber of animals sufficient for achieving and maintaining over multiplegenerations a stable balance between the rate of genetic improvement andthe rate of inbreeding, the SGN2 having a smaller number of animals thanthe SGN1, and the first and SGN2s being further genetically linked byuse of semen from the same sires in producing offspring in both thefirst and SGN2s; e. selecting dams for breeding from a ranking of damsin the SGN2 for achieving a measure of genetic improvement for a nextsucceeding generation in the SGN2, optionally a targeted measure ofgenetic improvement; and b. at intervals evaluating the measure ofgenetic improvement and using the measure for breeding the selected damsusing semen from sires in the SGN1 selected for use in breeding dams inthe SGN2 to achieve the measure of genetic improvement in the SGN2. 12.The Method of claim 11 wherein the SGN1 and the SGN2 comprise SGNs forproducing maternal line parent dams enriched in maternal traits forproducing terminal swine.
 13. The Method of claim 11 wherein offspringfrom the SGN1 and the SGN2 are evaluated for at least a core set ofphenotypic data and the core set is used for generating the ranking ofdams in the SGN2.
 14. The Method of claim 11 wherein dams from the SGN2are bred using semen from other lines, optionally from sires maintainedin a boar stud herds at the second site, for producing via one or morecrossbreeding steps, parent dams for producing terminal swine.
 15. TheMethod of claim 11 wherein the core set of phenotypic data comprises,for the first and SGN2s, reproductive data, off-test weight, and carcassdata.
 16. The Method of claim 11 wherein the core set of phenotypic datacomprises, for the SGN2, reproductive data and off-test weight.
 17. TheMethod of claim 11 wherein the core set of phenotypic data comprises,for the SGN2, only reproductive data.
 18. The Method of claim 11 whereinthe step of generating the ranking comprises use of a best linearunbiased prediction (BLUP) algorithm.
 19. The Method of claim 11 whereina dam herd for the SGN 1 comprises more than about 450 animals and asire line for the SGN1 comprises more than about 200 animals.
 20. TheMethod of claim 11 wherein a dam herd for the SGN2 comprises at leastabout 50 animals.
 21. A Method for determining measures for breedingswine comprising: a. accessing at least a core set of phenotypic dataobtained from each of a first swine genetic nucleus breeding herd SGN1and a second swine genetic nucleus herd SGN2, the SGN1 and the SGN2being genetically linked; and b. producing measures for at least one ofthe SGN1 and the SGN2 herds selected from the group consisting ofmeasures of estimated breeding values for selected traits and measuresof rate of genetic improvement and combinations thereof.
 22. The Methodof claim 21 comprising: a. producing measures for each of the SGN1 andSGN2 herds.
 23. The Method of claim 21 comprising: a. further accessingat least a core set of phenotypic data from each of an additional set ofswine genetic nucleus breeding herds, each SGN genetically linked withat least one other of a resulting total set of swine genetic nucleusbreeding herds SGNs; and b. producing measures for at least one of theresulting total set of SGNs.
 24. The Method of claim 21 wherein: a. themeasures of estimated breeding values are determined using a best linearunbiased prediction (BLUP) algorithm.
 25. The Method of claim 21wherein: a. phenotypic data from at least one of SGN1 and SGN2 areprovided by a data link to a database that is data linked to a dataprocessor for producing the measures of estimated breeding values. 26.The Method of claim 21 further comprising: a. Producing a measure ofrate of genetic improvement for at least one of SGN1 and SGN2.
 27. TheMethod of claim 21 further comprising: a. Producing a measure of rate ofgenetic improvement for at least one of SGN1 and SGN2; and b. Providingthe measure of genetic improvement via a data link to a site associatedwith the swine genetics breeding herd for which the measure is produced.28. The Method of claim 21 comprising: a. Producing a measure of rate ofgenetic improvement for at least one of SGN1 and SGN2; and b. Providingthe measure of genetic improvement via a data link to a site associatedwith the swine genetics breeding herd for which the measure is produced;c. Wherein the steps of producing and providing are conducted atmultiple optionally regular intervals; and d. Wherein the site receivingthe measures uses the provided measures for measuring compliance with apredetermined breeding plan for the swine genetics nucleus herdassociated with that site.
 29. The Method of claim 28 comprising: a.Improving compliance with the breeding plan upon occurrence of aprovided rate of genetic improvement differing from a target rate ofgenetic improvement associated with the breeding plan.
 30. The Method ofclaim 28 comprising: a. Adjusting a target rate of genetic improvementassociated with the breeding plan upon occurrence of a provided rate ofgenetic improvement differing from the target rate.
 31. A method ofproducing genetic improvement in swine comprising: a. accessing at leasta core set of phenotypic data obtained from each of a first swinegenetic nucleus breeding herd SGN1 and a second swine genetic nucleusherd SGN2, the SGN1 and the SGN2 being genetically linked; and b.producing measures for the SGN2 herd selected from the group consistingof measures of estimated breeding values for selected traits andmeasures of rate of genetic improvement and combinations thereof; f.generating a ranking of dams in the SGN2 herd for achieving a targetedmeasure of genetic improvement for a next succeeding generation in theSGN2 herd; and g. providing the ranking of dams in SGN2 herd for use forselection of dams for breeding using semen from SGN1 selected for use inbreeding dams in the SGN2 to achieve the targeted measure of geneticimprovement in the SGN2.